1. Field of the Invention
The invention relates to a transparent conductive film, a transparent conductive laminate therewith, a touch panel therewith, and a method for producing a transparent conductive film.
2. Description of the Related Art
Concerning conventional transparent conductive components, the so-called conductive glass is well known, which includes a glass member and an indium oxide thin film formed thereon. Since the base member of the conductive glass is made of glass, however, it has low flexibility or workability and cannot preferably be used in some applications. In recent years, therefore, transparent conductive films using various types of plastic films such as polyethylene terephthalate films as their substrates have been used, because of their advantages such as good impact resistance and light weight as well as flexibility and workability.
A known transparent conductive film for detecting input positions includes a transparent conductive layer having a predetermined pattern. However, such a patterned transparent conductive layer may produce a clear difference between the patterned portion and the non-patterned portion (pattern opening portion) so that a display device produced therewith may have a poor appearance. Particularly concerning capacitive touch panels having a patterned transparent conductive layer over the surface of the display unit, there has been a demand for a technique that can provide a good appearance to display devices even when transparent conductive layers are patterned.
In order to improve the appearance produced with a patterned transparent conductive layer, for example, Japanese Patent Application Laid-Open (JP-A) No. 2008-98169 proposes a transparent conductive film including a transparent film substrate, a transparent conductive layer and two undercoat layers different in refractive index placed between the transparent film substrate and the transparent conductive layer. The publication also discloses an example of such a transparent conductive film that includes a transparent film substrate, and a high-refractive-index silicon-tin oxide layer with a refractive index of 1.7 (10 nm or more in thickness), a low-refractive-index silicon oxide layer with a refractive index of 1.43 (30 nm in thickness) and an ITO film with a refractive index of 1.95 (15 nm in thickness) as a transparent conductive layer, which are formed in this order on the transparent film substrate.